Bird-Egg syndrome

Abstract

The bird-egg syndrome is often described in the literature as the association between initial sensitization to domestic birds proteins (parakeet, parrot, canary), and the allergic manifestations following egg yolk consumption, which appear later in time, through serum albumins cross-reactivity. The syndrome predominantly affects adults and less frequently children, who have a particular reactivity, due to the higher frequency of allergy to egg white. Chicken serum albumin (alpha-livetin, Gal d5), the allergen involved in the bird-egg syndrome, is a thermolabile and highly cross-reactive protein, capable to induce sensitization both by respiratory and digestive pathways. It is located in the plasma, in the muscle tissue of the birds, but also in the egg yolk. The most common clinical manifestations, also contact type dependent, are respiratory (asthma, rhino‑conjunctivitis) in the presence of birds aeroallergens and digestive (oral allergy syndrome, abdominal pain, vomiting, diarrhea) after consumption of partially cooked egg and chicken meat. Mild to moderate-severe systemic reactions (urticaria, angioedema, asthma) are also described in the literature. The diagnosis of the bird-egg syndrome requires the integration of patient`s history and paraclinical investigations into a clinical context. Allergy tests performed both in vivo and in vitro frequently show simultaneous reactivity to bird feathers, egg yolk and chicken meat. The bird-egg syndrome must be differentiated from the genuine allergy to poultry meat, which is considered to be a primary allergy and involves active sensitization to heat-resistant meat proteins. The main therapeutic method consists in strict avoidance of egg consumption and egg-derived products, including those containing traces, and avoidance, as much as possible, of aeroallergens such as feathers and bird droppings.